Methods for calculating routes, between two or more predefined geographic positions (e.g. by input of start point, destination point and/or intermediate destinations), are generally known. In these cases, calculated routes are normally determined as graphs of nodes and route segments, wherein, frequently, intersections or junctions correspond to the nodes, and portions between adjacent intersections or junctions correspond to the route segments.
Route segments and nodes may be described more fully by additional attributes that indicate, for example, a length of portions, a portion type, a maximum allowable travel speed, a direction of travel, type of intersection, etc. A route segment algorithm can use these attributes to determine weights for individual route segments, on the basis of which the optimum route is calculated. However, such weights can also be already fixedly assigned to the route segments and nodes in the cartographic data.
Frequently, search algorithms implement various search options, according to which it is possible to search for an optimized route between two selected positions. For example, selection of the option “fastest route” results in searching for a route having the shortest travel time, which does not necessarily at the same time have to be the route having the shortest distance. Such a refined search is made possible in that the route search algorithm gives preference, for example, to route segments for motorway portions over other route segments of the road network, appropriately modifying the weights of these portions (increasing or reducing them, according to the algorithm). Depending on the search option selected, a user can thus effect a search for a route, between two or more positions, that satisfies the quite particular travel criteria.
Known from DE 10 2010 027 777 A1 is a method for determining a consumption-optimized route between a start point and a destination point, in which energy consumption information is assigned to each route portion. The energy consumption information represents an additional consumption of energy relative to a minimum energy consumption, the energy consumption information being able to comprise a plurality of energy consumption values, which take account of a traffic flow characteristic on the assigned route portions. The energy consumption information is stored, together with the route portions, in a database.
The determination of a consumption-optimized route is additionally known from DE 10 2010 053 489 B3. In that case, a plurality of routes determined between a start point and a destination point are evaluated according to ecological criteria. The estimated fuel consumption for the routes is determined by means of a stored fuel consumption function, which specifies a minimum consumption in dependence on the speed.
Common to the known methods for determining a consumption-optimized route is the fact that they are based on partially simplified consumption models, and therefore frequently give only a rough prediction relating to energy-saving routes. On the other hand, the implementation of detailed consumption models that take account of, for example, characteristics of the traffic-route network, driver habits, vehicle parameters and a traffic situation, requires large amounts of computing capacity.